How to unlock a BMW with a dead battery
Asked by Jim Feb 16, 2015 at 01:31 PM about the 1984 BMW 5 Series 535i
Question type: Maintenance & Repair
My son has a 1984 535i that has been sitting a few months. The battery has died and the key will not unlock the door with no power. The windows are partially open, and we were able to reach in and pull up on the lock, but without power that won't work either. The AAA guy tried all the lock opening devices he had with no luck. We even tried hooking his battery to the tail lights. We were able to get interior lights to power up, but no enough power to make the locks work. I am at a complete loss as to how to get this car open so I can pop the hood and jump the battery.
10 Answers
The key doesn't unlock the lock in the door?
Will the key go into the lock cylinder but not turn? If that's the case get wd40 or PB Blaster and put the red straw into the cylinder and spray. Have a rag close by to wipe up the overflow. Now insert the key then take it out. Keep doing that over n over again then spray again. When you insert the keep trying to tutn the lock. At some point the lock will move. In might even take a day or so but it will move. Nobody uses a key in the door anymore because of the remote entry. So the lock doesn't get used and gets stuck. Last ditch would be call a mobile locksmith.
Key goes in the lock just fine, It turns just fine, but the lock is electronic and with a dead battery it will not unlock. The windows are partially open, and we even got an arm in the window, pulled up on the door lock but it would not unlock because it is electronic and the battery is dead.
Ahh I see. I would contact a BMW dealer or a European mechanic.
just put the key in the driver door side lock, and before you turn the key, left up the door handle and hold for few second and then turn the key left not clockwise and should unlock.
When you get in, take battery out recharge it, all locks should work again.
I would start with checking the battery voltage for a minimun of 12.5 volts, if i have that I would check 2 C if I the same at the switch input, and output. 1 of these voltages will be missing, or Negitage -12.5 volts D.C>
Have you tried to completely disconnect rhe battery for 10 - 15 mins to reset the computer? This procedure is standard for emissions, aka technical difficulties.
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